Something to try, will empty the dictionaries.
Minimal testing.
(defun c:DicSTYLEClean ( / dics dic dicName tmpname)
(vl-load-com)
(setq dics (vla-get-dictionaries
(vla-get-activedocument (vlax-get-acad-object))
)
)
(foreach dicname '("ACAD_MLEADERSTYLE" "ACAD_MLINESTYLE"
"ACAD_PLOTSTYLENAME" "ACAD_TABLESTYLE"
"ACAD_SCALELIST" "ACAD_VISUALSTYLE"
)
(if (or
(vl-catch-all-error-p
(setq dic (vl-catch-all-apply 'vla-item (list dics dicname))))
(null dic))
(prompt (strcat "\n+++ Dictionary " dicname " does not exist."))
(progn
(prompt (strcat "\nProcessing Dictionary " dicname " ."))
(vlax-for item dic
(setq TmpName (vla-getname dic item))
(if (or (member (strcase TmpName) '("DEFAULT" "STANDARD"))
(vl-catch-all-error-p (vl-catch-all-apply 'vla-delete (list item)))
)
(prompt (strcat "\n Dictionary entry " TmpName " can not be deleted."))
(prompt (strcat "\n *** Removed " TmpName " from dictionary."))
)
)
)
)
)
(princ)
)